Here’s a notable Getty pic from the April 27, 2016 Mayflower Hotel event—Kislyak & Sessions both named in the official caption pic.twitter.com/epubUUfkKc
— Kerry Eleveld (@kerryeleveld) June 1, 2017
Additional attendees included Bud McFarlane (source), Russian Ambassador Sergey Kislyak (source), Italian Ambassador Armando Varricchio (source machine translation), and the Singapore Ambassador. Source
There are many rumors that the Mayflower meeting was significant, possibly where deals were struck relating to the conspiracy. Nothing appears to be publicly confirmed, other than the attendees appearing to be involved in aspects of the conspiracy, and several participants having repeatedly lied about the event.